A radio access scheme and a radio network (below referred to as “long term evolution (LTE)” or “evolved universal terrestrial radio access (EUTRA)”) of the cellular mobile communication is examined in the 3rd Generation Partnership Project (3GPP). In LTE, a base station device is also referred to as an evolved NodeB (eNodeB), and a terminal device is also referred to as a user equipment (UE). The LTE is a cellular communication system in which a base station device covers an area, and a plurality of such areas is disposed so as to have a cell shape. A single base station device may manage a plurality of cells.
The LTE corresponds to time division duplex (TDD). LTE employing a TDD scheme is also referred to as TD-LTE or LTE TDD. Here, in TDD, an uplink signal and a downlink signal are subjected to time division duplex.
The 3GPP has examined that DL-UL Interference Management and Traffic Adaptation is applied to the TD-LTE. The traffic adaptation technique is a technique in which a ratio between uplink resources and downlink resources is changed depending on traffic of an uplink and traffic of a downlink. Here, the traffic adaptation technique is also referred to as dynamic TDD.
In NPL 1, a method using a flexible subframe is proposed as a method for realizing traffic adaptation. A base station device can receive an uplink signal or transmit a downlink signal in a flexible subframe. In NPL 1, a terminal device considers a flexible subframe as a downlink subframe as long as the base station device does not perform an instruction of transmission of an uplink signal in the flexible subframe.
NPL 1 discloses that a Hybrid Automatic Repeat reQuest (HARQ) timing for a physical downlink shared channel (PDSCH) is determined based on a UL-DL configuration (uplink-downlink configuration) (also referred to as a UL/DL configuration) which is newly applied, and a HARQ timing for a physical uplink shared channel (PUSCH) is determined based on the previous UL-DL configuration.
NPL 2 discloses (a) that a UL/DL reference configuration is applied, and (b) that a certain subframe may be scheduled for any of an uplink and a downlink by dynamic grant/assignment from a scheduler.